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A large portion of the population suffers
from dry skin. Different forms and degrees of severity can be distinguished.
Dry skin is especially common in children under 10 and older people
over 60. Between the ages of 10 and 60, significantly more women than
men suffer from dry skin. Some 15 to 20 percent of the population
suffer from an atopic disposition to dry skin (xerodermia). |
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Skin dryness is dependent on various external (exogeneous)
and internal (endogenous) factors. Typical exogenous factors are climate
and environmental factors, including skin contact with chemicals like
cleansing agents and solvents. Further exogeneous factors are UV exposure,
the influence of skincare and therapeutic preparations such as medicines
(topical and systemic).
On the other hand, the endogenous factors that lead to dry skin or
contribute to its development, include genetic predisposition, biological
skin ageing, hormonal influence and certain dermatological and internal
diseases (neurodermatitis, psoriasis, ichthyosis, diabetes).
Forms of dry skin
There are a variety of causative factors and levels of severity of
dry skin, from mild to clearly pathological forms. In practice, the
individual forms are not always clearly distinguishable. However,
in general one can distinguish between problem dry skin and extremely
dry skin. In both types, the cause is essentially a deficit of natural
moisturising factors, especially urea. A special form, due to its
pathogenesis, is atopic dry skin, in which a disturbed fatty acid
metabolism of the skin plays a major role.
Problem dry skin
Characteristics of problem dry skin are:
 mild scaling
roughness
a feeling of tightness
possibly itching
The reduced water binding capacity is an important factor in problem
dry skin. This depends on the concentration of natural moisturising
factors (NMF), the most important of which are urea and amino acids,
as well as on epidermal lipids (particularly triglycerides, free fatty
acids, cholesterol). Urea is formed during the breakdown of specific
amino acids, particularly arginine, in the cell cornification process.
In cornification disorders, there is a deficiency of these amino acids,
particularly arginine. This leads to a marked reduction in the concentration
of urea, and the natural moisturising function is reduced. In comparative
measurements clinically dry skin was shown to have a 50 percent lower
urea concentration than healthy skin. This lack of natural moisturising
factors causes increased transepidermal water loss (TEWL) and eventually
skin dehydration with its typical symptoms. |
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Urea, a natural moisturising factor, increases
the water binding capacity of the skin. A lower urea concentration
results in a higher transepidermal water loss. |
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An application of a skincare preparation containing
approximately 3 to 5 percent urea can compensate for the deficit in
natural moisturising factors. An increase in the water binding capacity
of the skin follows and the skin condition improves or is normalized.
Extremely dry skin
The characteristics of extremely dry skin found for example in the
elderly or on the hands after extreme dehydration are:
roughness
chapping with a tendency
to formation of rhagades
callus formation
/ scaling
frequently itching
Unlike with problem dry skin, the application of a low concentration
of urea is not sufficient for extremely dry skin. Often a therapy
with formulations containing 10% urea is required.
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Atopic dry skin
Some 15 to 20 percent of the population suffer from atopic dry skin,
which predisposes them to neurodermatitis. The result can be:
scaling, rough skin
with lichen formation (skin thickening, cracking) and rhagades
intensive itching
tendency to reddening
and inflammation (atopic eczema)
Besides a deficiency of natural moisturising factors, especially urea,
there is a disturbed fatty acid metabolism. This leads to qualitative
and quantitative changes in the barrier lipids and so to a breakdown
of the barrier function. |
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Atopic eczema |
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Causes and treatment of
atopic dry skin conditions
In people with atopic dry skin, despite a sufficient intake of the
essential omega-(n)-6 fatty acid, the concentration of linoleic acid
and its metabolites such as gamma linolenic acid is markedly reduced
in the epidermis. At the same time, there is an excess of the monounsaturated
omega-9 fatty acids, especially oleic acid. This leads to increased
formation of dysfunctional ceramides esterified with oleic acid in
atopic dermatitis rather than the physiological ceramides that are
especially rich in linoleic acid.
This deficiency has wide-ranging consequences for the skin condition
of the neurodermatitis sufferer. Systemical and topical application
of omega-6 fatty acids can thus have a beneficial effect.
In addition to oral substitution, the application of omega-6 fatty
acid-containing skincare products has proved effective, as they contain
a high proportion of linoleic acid and gamma
linolenic acid and can be applied directly to the skin. Especially
in children, the combination of oral and topical application of essential
fatty acids in the form of evening primrose oil is a proven and very
safe treatment concept (the "sandwich" therapy). |
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Evening primrose oil, which can be applied both orally and topically,
is characterized by its richness in highly beneficial linoleic and
gamma linolenic acid (together approximately 85 percent) and a clinically
proven skin compatibility. |
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Ceramides: the most important
barrier-forming lipids
When there is a deficiency of long-chained essential fatty acids -
especially linoleic acid and gamma linolenic acid - a change in the
ceramides follows: This group of substances forms what is known as
the lipid barrier between the horny cells - similar to the mortar
between the bricks of a wall - which plays a central role in the regulation
of moisture in the skin. Thus the stability and functionality of the
permeability barrier is dependent on a sufficient supply of essential
fatty acids.
Scientific tests have shown that locally applied omega-6 fatty acids
are absorbed directly into the linoleic acid-dependent lipid structure
and thus restore the diminished barrier function in the atopic patient.
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Intact lipid membrane
1 Ceramides
2 Cholesterol
3 Free fatty acids
The disturbed lipid membrane in atopic patients with quantitative
and qualitative alteration of the lipid structure.
1 Oleic acid |
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Other factors in atopic dry skin
Besides the above-mentioned factors an extreme shortage of the natural
moisturising factor urea plays an important role in the atopic dry
skin. If severe, this leads to a reduced water binding capacity of
the skin. Skincare preparations with a high urea content can balance
out this deficiency in the patient with neurodermatitis. |
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Optical microscope image of "normal skin",
dry skin and eczematous skin.
1 Horny layer
2 Epidermis (uppermost skin layer)
3 Dermis/papillae |
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